A disc drive typically includes one or more discs having digital information magnetically or optically stored thereon. The discs are rotated at a constant high speed by a drive motor, which may be a spindle motor, during operation of the drive. In a typical magnetic disc drive, information is written to and read from tracks on the discs through the use of an actuator assembly, which rotates during a seek operation. A typical actuator assembly includes a plurality of actuator arms, which extend towards the discs, with one or more flexures extending from each of the actuator arms. Mounted at the distal end of each of the flexures is a transducer mounted on a head, which acts as an air bearing slider enabling the head to fly in close proximity above the corresponding surface of the associated disc.
Increasing the density of information stored on discs can increase the storage capacity of disc drives. To read the densely stored information, designers have decreased the gap fly height between the heads and the discs. Reducing the gap fly height can lead to increased contact between the head and the data portion of the disc during operation of the disc drive (i.e., head-disc interference). Such interference can excite head and disc resonance frequencies, which can interfere-with the servo positioning of the recording transducers over the data tracks. For example, if head-disc interference occurs during a servo track writing operation, then spurious vibrations may be written into the servo pattern due to the excitation of head and disc resonance modes. Head-disc interference can also lead to accelerated head and disc surface wear. This may culminate in a “head crash,” a phenomena where the recording head irreparably damages the disc surface, resulting in loss of data and catastrophic disc drive failure.
Head-disc interference is particularly likely if the disc surfaces are not sufficiently flat. Even if discs are flat before being mounted on the spindle motor, the disc clamp that secures the discs to the spindle motor may deform the discs by applying uneven pressure to the discs sufficient to increase head-disc interference.
Accordingly there is a need for a disc clamp that more evenly distributes clamping pressure applied to the discs. The present invention provides a solution to this and other problems, and offers other advantages over the prior art.